Although ApoE2 expression protects against AD, its expression is associated with the increased incidence of familial type III hyperlipoproteinemia—a disorder characterized by an inability to metabolize lipids including cholesterol and triglycerides.[6] ApoE isoforms have also been implicated in the development of Parkinson’s disease [7], vascular pathology [8], and most recently, COVID-19 prognosis[9]. Here, APOE is linked to Alzheimer disease.